Evaporator structure in refrigeration apparatus



Oct. 19, 1954 Filed Dec. 13. 1951 2 Sheets-Sheet 1 TTz INVENTOR JULES N.SALER ATTORNEY Oct. 19, 1954 J. N. SALER 2,691,371

EVAPORATOR STRUCTURE IN REFRIGERATION APPARATUS Filed Dec. 13, 1951 2Sheets-Sheet 2 F|G 5 4 INVENTOR JULES N. SALER ATTORNEY Patented Oct.19, 1954 EVAPORATOR STRUCTURE IN REFRIG- ERATION APPARATUS Jules N.Saler, Springfield, Mass, assignor to Westinghouse Electric Corporation,East Pittsburgh, Pa., a corporation of Pennsylvania Application December13, 1951, Serial No. 261,443

6 Claims. (Cl. 62-115) This invention relates to refrigeration apparatusand, more particularly to means for rapidly and effectively defrostingsuch apparatus.

It is an object of this invention to provide an improved refrigeratingand defrosting system for selectively refrigerating and defrosting arefrigerant evaporator.

It is another object of this invention to provide a novel evaporatorstructure for a refrigerating and defrosting system.

These and other objects are effected by the invention as will beapparent from the following description and claims taken in connectionwith the accompanying drawings, forming a part of this application, inwhich:

Fig. 1 is a top plan view of the evaporator structure employed in thisinvention;

Fig. 2 is a rear elevation view of the evaporator structure;

Fig. 3 is an end elevation view of the evaporator structure;

Fig. 4 is a vertical, enlarged, cross-section view of the evaporatorstructure taken along the lines IV-IV of Fig. 2; and

Fig. 5 is a diagrammatic view of a refrigerating and defrosting systemconstructed in accordance with this invention.

Referring to the drawings, the numeral Iii designates generally arefrigerant evaporator structure of box-like configuration having anopening l2 in the front thereof for the reception of ice trays (notshown) and foods to be frozen or cooled to a low temperature. Theevaporator structure It is adapted to be mounted within an insulatedcabinet structure (not shown) of any suitable construction.

The evaporator structure I0 is of sectional or composite constructionand consists of an L- shaped portion I l forming the top and back wallsof the evaporator structure and a U-shaped portion [6 forming the bottomand side walls of the evaporator. The L-shaped portion I4 is constructedof superimposed metal sheets [8 and 2H, portions of which sheets areembossed to form refrigerant passages between the sheets. After forming,these sheets are secured together in any suitable manner such as bywelding or brazing. Formed within the back wall portions of the L-shaped evaporator portion I4 is an inlet passage 22. Both evaporatorsheets l8 and are struck inwardly forming the refrigerant passage 22 toprovide a recess on the exterior surface of the evaporator back wall forthe reception of an electric heating element 25, the purpose of whichwill hereinafter be described. The inlet passage 22 extends along thebottom edge of the evaporator back wall, up the side edge thereof andcommunicates with an upper portion of a storage vessel 26 likewiseformed by and between the back wall portions of the L-shaped sheets i8and 20. A pair of outlet passages 23 and 30 communicate with upper andlower portions, respectively, of the storage vessel 26 and are joined ata point 32 near the upper edge of the storage vessel 26. The upperoutlet passage 28 is provided with a restriction 34 which may be formedby crimping the passage 28 or by placing a fixed restriction within thepassage 28 before assembling sheets is and 2G. The lower outlet passage38 continues along the upper edge of the evaporator back wall andcommunicates with a sinuous refrigerant passage 35 formed by and betweenthe top wall portions of the L-shaped sheets I8 and 20.

The U-shaped portion l6 of the evaporator structure it is likewiseformed by two superimposed metal sheets 31 and 38 having refrigerantflow passages formed therebetween, which, for the sake of simplicity,have been shown as parallel passages 39 extending from the upper portionof one side wall downwardly, across the bottom wall, and upwardly to theupper portion of the opposite side wall. The refrigerant passages 39 areconnected at one end by an inlet header 4!] and at the other end by asuction or outlet header 42.

The two portions i l and iii of the evaporator structure it areoperatively connected to form a continuous refrigerant fiow passage by aconduit Ml connecting the outlet end (it of the sinuous passage 36 withthe inlet header 40 on the side wall of the U-shaped evaporator portion[5.

As in a conventional refrigerating system, apparatus is provided forsupplying refrigerant to and withdrawing refrigerant from the evaporatorstructure it]. As shown in Fig. 5, this apparatus includes amotor-driven compressor 48, a condenser 50, a hot gas conduit 52 forconveying refrigerant compressed by the compressor 48 to the condenser50, a capillary tube 54 for conveying refrigerant condensed by thecondenser 5E3 to the inlet passage 22 of the evaporator structure l0,and a suction or return conduit 56 for conveying refrigerant from theoutlet header 42 on the evaporator structure It] to the compressor 48.As shown in Fig. 5, the return conduit 56 is soldered to or otherwisearranged in heat exchange relationship with portions of the capillarytube 54 and the hot gas line 52.

Power to operate the refrigerating and defrosting system is provided byelectric supply lines L1 and L2 under the control of a thermostaticswitch 58 connected in series with the leads 6U, 62 and 64 supplyingpower to the motor compressor 48. Switch 58 is actuated in response topressure changes within a temperature-sensitive bulb 66 secured to aportion of the evaporator structure It to energize and deenergize themotor compressor 48 to maintain the desired temperature of theevaporator structure I 0, as is well understood. Currenttoenergizetheelectric heating element 224 is'li-kewise derived fromlinesL1 and L2 through lead 60, switch 58,'leads '62, 68 and 10, throughswitch 12 and lead 14. It will be noted that the thermostatic controlswitch 58 is also in series with the supply :circuit5for the heater 24and, therefore, the heater may be energized by the switch 12 only-duringthose periods when the motor compressor 48 is energized.

Referring to Fig. 5, the operation of .the improved refrigerating anddefrosting system is as follows: During a refrigerating operation, :theswitch 72 is open and heater 24 is deenerz d- The refrigerant from thecompressing and condensing apparatus is conveyed through capillary tube54 and enters the evaporator structure 19 through inlet passage 22."This refrigerant, the major portion of which is in a liquid state,flows into and floods or completelyfills storage vessel 26, outletpassages 28 and 3t and flows into passage 36 in the top wall of theevaporator structure l0. Partial evaporation of the liquid refrigeranttakes place in passagetfi and the resulting mixture of liquid andgas'fiows through connectingconduit 44 and header 4%! into therefrigerant passages 39 of the U-shape portion it of the evaporatorstructure. As the refrigerant absorbs further heat from the food stuffsin the evaporator structure It and the surrounding air, it is convertedentirely to gas which passes through the outlet header 42 and isconveyed back to the compressing and condensing apparatus by the returnconduit 56.

During the refrigerating operation, any gaseous refrigerant which may beconveyed to or gen erated in the storage vessel 25 will escape throughthe upper outlet passage 28 and will be carried through the remainingrefrigerant passages by the liquid refrigerant-flowing .therethrongh.The restriction .34 inthe outlet passage 28 is of sufficient size topermit the escape of all gaseous refrigerant trapped inthe storagevessel during the refrigerating operation.

Due to the fact thattheevaporator structure L0 is maintained at atemperature below 32 F., frost will collect thereon and .must .beremoved to ensure efficient operation of the system. The removal offrost is effected by closing switch '12 to energize heater 215 whichappliesheat to the refrigerant flowing through .inlet passage .22 .oftheevaporator structure iii. Since the. heater. is so located as toapply heat to the refrigerant flowing through the system, it isdesirablethat the heater be energized only during ,a running period of thecompressor 48. As previouslynoted, this condition of operationiseifected by ,having the thermostatic switch58 in series .withthesupply circuit of the .heater 2.4. .Should the switch .12 .be closedduring a shutdown ,period of the compressor 43, defrosting will merelybedelayed until the next running period of the-compressor 48 ascontrolled by the thermostatic sWitchSB. and its .associatedtemperature-sensitive bulb .66.

The heat applied to the refrigerant flowing through inlet passage 2.2vaporizes a major portion of this refrigerant and increases thequantityof gas in the storage vessel. 26. Because .of the restriction 3B in theupper .outletpassage28, only a portion of this gas is permitted toescape from the storage vessel 26, whereupon the pressure in thestorage'vessel :25 rises sufficiently to force the liquid refrigerantcontained therein outthrough the-lower outlet passage 3-0-and=int0 theremaining refrigerant flow passages 35 and 39 in the evaporatorstructure It. The storage vessel 25 contains sufficient liquidrefrigerant to flood the remaining refrigerant fiowipassages 36 and 39as well as the headers 40 and *42 of the evaporator Hi and cause someliquid refrigerant to be spilled over into the return conduit 56. A:portion of 'the'liquid refrigerant in return conduit'zfi'fi-isvaporized by the heat derived through the heatexchanger between thereturn conduit '56 and the capillary tube 54 and the remaining liquid isvaporized 'by heat derived through the heat exchanger between the returnconduit 56 and the hot gas line 52. This vaporization of liquidrefrigerant returning to the compressor causes an increase in theoverall pressure in the lower pressure side ofthe refrigerating systemand materially aides in the defrosting operation. The major defrostingaction is attained, however, bythecondensation of the'hot gaseousrefrigerant issuing from the heated portion-of the inlet passage 22.This hot gas is "forced through the Various refrigerant passages'in theevaporator structure It and, in condensinggives up heat to the wallportions of the evaporator!!! to melt the frost which has collectedthereon. The refrigerant thus condensed is revaporized in"the'return'conduit 56'by the "heat exchangers between the returnconduit 56 and thecapillary tube 54 and the hot gas line-52.

When defrosting is complete, the switch 12 is opened to deenergizetheheaterffl'andpermit the system to'return'to refrigerating operation.

If desired, automatic control means may be provided for closing andopening switch .12 in response to the various conditions indicating thecollection of frost and the absence of frost on the evaporator. Sucha.control is describedand claimed in U. S. Patent "No. 2,595,967,granted May 6, 1952 to Graham's. 'McQloy and assigned to the assignee ofthe present invention.

"It will be apparent from the foregoing that this invention contemplatesthe construction of a refrigerating and defrosting system in which astorage vessel is formed by and between the superimposed sheets of theevaporator structure for "the purpose of collecting and dischargingliquid refrigerant. This construction is economical andpermits of easeof assembly as compared to prior refrigerating and defrosting systemswherein the :storage vessel was formed independently of the otherelements ofthe system. It will further be noted that the novelarrangement of outlet passages from the storage vessel insures positivedischarge of the liquid contents of the vessel during defrosting and yetallows the vessel to collect a maximumamountof liquid refrigerant duringthe refrigerating operation.

While I have shown my invention inbutone i-Qrm, it will be obvious tothose skilledintheart that it .not .so limited, butis susceptible ofvarious changes and modifications without departing from the. spiritthereof.

What I claim is:

1. In a refrigerating and defrosting system, the combination of arefrigerant evaporatorcomprising superimposed sheets, first and secondrefrigerant passages each having inlet and outlet ends and'formed by andbetween said evaporatorsheets, a compresson-a condensenfirst conduitmeans for conveying compressed refrigerant frqm-saidcompressor to said"condenser, second conduit means including-afiow impeding'deviceforconveying refrigerant-condensed by said condenser to the'inlet endof-said first refrigerant passage, third conduit .-means for conveying,

refrigerant from the outlet end of said second refrigerant passage tosaid compressor, said third conduit means having a portion thereofarranged in heat exchange relationship with the refrigerant compressedby said compressor, a storage vessel formed by and between saidevaporator sheets, said first refrigerant passage having the outlet endthereof communicating with said storage vessel, a first outlet passagecommunicating at one end with a lower portion of said storage vessel andat its other end with the inlet of said second refrigerant passage, asecond outlet passage communicating at one end with an upper portion ofsaid storage vessel and at its other end with said first outlet passage,said second outlet passage having a restriction therein, theconstruction and arrangement being such that liquid refrigerantaccumulates in said storage vessel during refrigerating operation ofsaid system, and means for appiying heat to the refrigerant flowingthrough said first refrigerant passage to vaporize at least a portion ofsaid refrigerant to increase the pressure in said storage vessel wherebythe refrigerant liquid contained therein is forced out of said vesselthrough said lower outlet passage, said storage vessel containingsufficient refrigerant liquid to flood said second refrigerant passageand spill over into said third conduit means.

2. In a refrigerating and defrosting system, the combination of arefrigerant evaporator comprising superimposed sheets, first and secondrefrigerant passages each having inletand outlet ends and formed by andbetween said evaporator sheets, a compressor, a condenser, first conduitmeans for conveying compressed refrigerant from said compressor to saidcondenser, second conduit means including a flow-impeding device forconveying refrigerant condensed by said condenser to the inlet end ofsaid first refrigerant passage, third conduit means for conveyingrefrigerant from the outlet end of said second refrigerant passage tosaid compressor, a storage vessel formed by and between said evaporatorsheets, said first refrigerant passage having the outlet end thereofcommunicating with said storage vessel, said second refrigerant passagehaving the inlet end thereof communicating with said storage vessel, theconstruction and arrangement being such that liquid refrigerantaccumulates in said storage vessel during a refrigerating operation ofsaid system, and means including a heater arranged in heat exchangerelationship with said first refrigerant passage for heating anddischarging the contents of said storage vessel into said secondrefrigerant passage to effect defrosting of said evaporator.

3. In a refrigerating and defrosting system, the combination of arefrigerant evaporator comprising superimposed sheets, first and secondrefrigerant passages each having inlet and outlet ends and formed by andbetween said evaporator sheets, a compressor, a condenser, first conduitmeans for conveying compressed refrigerant from said compressor to saidcondenser, second conduit means including a flow-impeding device forconveying refrigerant condensed by said condenser to the inlet of saidfirst refrigerant passage, third conduit means for conveying refrigerantfrom the outlet end of said second refrigerant passage to saidcompressor, a storage vessel formed by and between said evaporatorsheets, said first refrigerant passage having the outlet end thereofcommunicating with said storage vessel, a pair of outlet passagescommunicating respectively with upper and lower portions Of said vessel,said upper outlet passage having a restriction therein, said secondrefrigerant passage having the inlet end thereof communicating with saidvessel outlet passages, the construction and arrangement being such thatliquid refrigerant accumulates in said storage vessel duringrefrigerating operation of said system, means including a heaterarranged in heat exchange relationship with said first refrigerantpassage for heating and discharging the contents of said storage vesselinto said second refrigerant passage to effect defrosting of saidevaporator, said storage vessel containing sufficient refrigerant liquidto flood said second refrigerant passage and spill over into said thirdconduit means, and means for vaporizing the refrigerant liquid spilledinto said third concluit means.

4. A defrostable refrigerant evaporator unit comprising a pair ofsuperimposed L-shaped sheets adapted to form the top and back walls of astorage compartment, a refrigerant storage vessel formed by and betweenthe back wall portions of said sheets, an inlet passage and a pair ofoutlet passages for said vessel, said passages being formed by andbetween said sheets, said outlet passages communicating respectivelywith upper and lower portions of said vessel, a sinuous passage formedby and between said L -shaped sheets, at least the major yortion of saidsinuous passage lying in the top wall portion of said sheet, saidsinuous passage having the inlet end thereof connected to said storagevessel outlet passages, and an electric heating element arranged in heattransfer relation with said inlet passage.

5. A defrostable refrigerant evaporator unit comprising superimposedsheets, at least a portion of said sheets lying in a substantiallyvertical plane, a storage vessel formed by and between the verticalportions of said sheets, a refrigerant inlet passage and a pair ofoutlet passages for said vessel, said passages being formed by andbetween said sheets, said outlet passages communicating respectivelywith upper and lower portions of said storage vessel, a fourthrefrigerant passage formed by and between said sheets, said fourthpassage having the inlet end thereof connected to said pair of outletpassages, and an electric heater arranged in heat transfer relation withsaid storage vessel inlet passage.

6. A defrostable refrigerant evaporator unit comprising superimposedsheets, at least a portion of said sheets lying in a substantiallyvertical plane, a storage vessel formed by and between the verticalportions of said sheets, a refrigerant inlet for said vessel, a pair ofoutlet passages for said vessel, said passages being formed by andbetween saicl sheets, said outlet passages communieatin respectivelywith upper and lower portions of said storage vessel, said upper outletpassage being formed with a restriction therein, and a third refrigerantpassage formed by and between said sheets, said third passage having theinlet end thereof connected to said pair of outlet passages.

References Cited in the file of this patent UNITED STATES PATENTS NumberName Date 2,459,173 McCloy Jan. 18, 1949 2,544,938 Phillip Mar. 13, 1951

